Windows NT 3.x 3.51

Windows NT 3.1 was the first of the Windows NT series. Sporting the same face as its consumer counterpart Windows 3.1, it was completely different under the hood. A true 32-bit native operating system, Windows NT descended from the work Microsoft did while collaborating with IBM on OS/2 after the great split, and bringing in former DEC employees like Dave Cutler, bringing a VMS influence into the system. It was followed up by Windows NT 4.0.